Chassis Battery Voltage

Topic: Chassis Battery Voltage (Read 2040 times) previous topic - next topic

Re: Chassis Battery Voltage

Reply #25 – February 11, 2018, 01:29:15 pm

One reason a boost solenoid may not get 12 volts when dash boost switch is on: If the dash switch is powered by start battery bank, it will not have enough voltage to power solenoid.
It depends where the dash switch gets its power source. I could get power from both battery bank with diodes, or a manual switch could choose which bank to power dash switch.

Re: Chassis Battery Voltage

Reply #26 – February 11, 2018, 03:13:29 pm

Thanks Pierce, I need to do some more digging in my books to see if it does have some charger to charge the coach batteries. That will let me know weather I need to fix something or add something besides a buzzer if I leave the lights on again.

Re: Chassis Battery Voltage

Reply #27 – February 11, 2018, 03:20:08 pm

Thanks Barry, I will have to do some more testing once I get it running again, at the least I know the light in the switch has never lit up

Re: Chassis Battery Voltage

Reply #28 – February 11, 2018, 06:23:53 pm

Boost sw. on light can be fixed. Just pull out the sw. and you can remove the piece that holds the light bulb. Bulbs are available at most auto parts stores. (just did mine) Have a great day ---- Fritz

Re: Chassis Battery Voltage

Reply #29 – February 11, 2018, 06:49:44 pm

Thanks Fritz, I will have to get it working first as from what I have read if the solenoid does not work the light may not come on anyway??

Re: Chassis Battery Voltage

Reply #30 – February 11, 2018, 07:38:03 pm

Quote from: Super8mm – February 11, 2018, 03:13:29 pm

Thanks Pierce, I need to do some more digging in my books to see if it does have some charger to charge the coach batteries. That will let me know weather I need to fix something or add something besides a buzzer if I leave the lights on again.

Steve.

When you plug into shore power, the OEM charger starts charging only the house batteries. Many forum members have had problems with the OEM charger and have boiled their batteries. Ours works fine and the photo I posted was taken today. There are a couple dozen reasons to have the twin voltmeters on the dash where you can monitor them driving or in storage. It gives you an instant picture of alternator output, charger health, house battery voltage after watching TV half the night etc. I tie them together while parked so I don't need a separate charger. I have connected a trickle charger to the engine batteries and used the connecting cable to keep both fully charged but this arrangement is perfect. You do have to unplug the two male lighter plugs before you go anywhere. I like the 13.1 volts but would go to a different charger if the voltage were to exceed 13.5V or drop below 13V. I just used a zip cord to tie the two together. The cord or plugs never even get warm. It pays to visit the coach frequently and check voltages as batteries are expensive. I do have the voltmeters on a switch so I don't have to have them visible all the time, especially at night. They get their respective readings off of the Audit wires. The color codes/numbers shown for the Audit in a separate schematic.

Pierce

Re: Chassis Battery Voltage

Reply #31 – February 11, 2018, 10:38:18 pm

Thanks Pierce, I will look around my dash and see where I can mount a pair of gauges

Re: Chassis Battery Voltage

Reply #32 – February 11, 2018, 11:26:39 pm

Quote from: Super8mm – February 11, 2018, 10:38:18 pm

I will look around my dash and see where I can mount a pair of gauges

Post linked below shows the inexpensive volt meters I installed about 6 months ago. They have been working perfectly. I really like being able to quickly and easily check the relative voltage on both battery banks, both while driving and while parked.

What did you do to your coach today VI

Re: Chassis Battery Voltage

Reply #33 – February 12, 2018, 12:45:21 am

Quote from: Chuck & Jeannie – February 11, 2018, 11:26:39 pm

Post linked below shows the inexpensive volt meters I installed about 6 months ago. They have been working perfectly. I really like being able to quickly and easily check the relative voltage on both battery banks, both while driving and while parked.

Looks good Chuck, I will have to do some measuring and see where I have some space. My dash is a lot different than yours.

Re: Chassis Battery Voltage

Reply #34 – February 12, 2018, 06:56:08 am

Quote from: Super8mm – February 12, 2018, 12:45:21 am

I will have to do some measuring and see where I have some space. My dash is a lot different than yours.

Steve,

You should have the luminescent dash in your coach. (seems like buy your build number they had added them to the 270s) Doing a cut out in the aluminum dash sections can have devastating effects on the way the dash lights up. Now if the luminescent dash lighting system is dead already then there is no harm.

Mike

Re: Chassis Battery Voltage

Reply #35 – February 12, 2018, 07:06:17 am

Yes Mike I do have the luminescent dash, I have one spot about 1/4" long in the bottom left corner that does not work but it appears that the rest of it is OK and still lights up.

Re: Chassis Battery Voltage

Reply #36 – February 16, 2018, 08:27:01 pm

Well today it was above freezing and I went to the coach and did some testing.

First of all after I charged the batteries over night last weekend they were still up today and it started right up.

Next I found the isolator and below it are two solenoids. I take it one is for the Boost and not sure what the other one is for.

When I measured the voltage on the front one from large terminal to the other large terminal it was around 13.4 volts. The other one bounced around some but it looked like about 117 volts??? It didn't seem to make any difference if the Boost switch was on or not.

When I check the small terminal on the front one there was just minimal voltage like 1.2 to 2 volts.

Re: Chassis Battery Voltage

Reply #37 – February 16, 2018, 08:58:05 pm

Steve, Solenoids: 1 each for Boost (small wire from dash boost switch) & Starting (small wire from ignition key start position (through neutral-start relay located on front panel) . . . Manually put 12 volts on small boost solenoid will connect both battery banks. Manually put 12 volts on start solenoid will crank engine.

Re: Chassis Battery Voltage

Reply #38 – February 16, 2018, 09:05:40 pm

Thanks Barry, so the rear one is the starter solenoid?

If I have 13 volts going through the front solenoid is that sending the 13 volts to the chassis batteries?

Re: Chassis Battery Voltage

Reply #39 – February 17, 2018, 12:18:08 am

Steve, On the boost solenoid, one of the big cables is connected to house battery bank. The other big cable is connected to start battery bank. If solenoid works, when its small wire is powered, the two banks of batteries are connected together. And the current flows from the bank with the higher voltage to the bank with the lower voltage. Current flow direction has nothing to do what a voltage actually measures, as current will always flow from high to low, no matter what the voltages are. When engine is off and house battery is being charged, the start bank usually has the lower voltage, so in this case current flows to start batteries.

Re: Chassis Battery Voltage

Reply #40 – February 17, 2018, 12:53:23 am

Thanks Barry, next time out I will air it up so I can get under it and follow the wire from the starter to the solenoid to see which one is for the starter then label it and the other one for the batteries, that way CRS wont bite me to hard the next time

Re: Chassis Battery Voltage

Reply #41 – February 17, 2018, 09:06:03 am

Steve,

It is easy to tell the solenoids apart, just from looking at your photos.

What you have labeled as "front" is your AUX START solenoid. It has light gauge wires attached to both large posts. One of the large posts should always show 12 volts - the other large post should only show 12 volts when the ignition switch is turned to "start". Turning your ignition switch to "start" powers the small solenoid post. This closes the solenoid switch, which in turn sends 12 volt power to the STARTER solenoid. Then your engine (hopefully) starts.

What you have labeled as "rear" is the BOOST solenoid. It has heavy battery cables attached to both of the large posts. The only function of this solenoid is to allow connection of the two battery banks (for whatever reason).

When you measure the voltage on any solenoid, you don't measure across the two large posts on the solenoid - you must measure each large post individually. Read the voltage on one large post, then move your probe to the other large post and read the voltage there.

Checking the BOOST solenoid with the boost switch OFF, the small post on the solenoid should not show any voltage, and you should read start battery voltage on one large post, and coach battery voltage on the other large post. Under most conditions, they will be different. With the boost switch turned ON, the small post will show 12 volts and both large posts on the BOOST solenoid should read identical voltage. If they don't, the solenoid is not closing/functioning correctly.

Re: Chassis Battery Voltage

Reply #42 – February 17, 2018, 10:06:21 am

Another thought:
Those 2 rusted square blobs ( just below and to the left of the "F" in front) in your pics. that have wires coming off of them are self resetting breakers. The one on the right is for the condenser fan this is a 20 amp breaker. The one on the left is for the dash A/C compressor clutch and it also has the alternator sense wire hooked up to it. This one should be a 15 amp. Some people have moved the sense wire to a better location to keep from getting a low voltage indication when the compressor kicks in. The pics. show that the lugs are covered in rust/corrosion and this area needs to be cleaned up for proper voltage readings to the alternator. Both of these should get there power feed from the aux. start solenoid.

Do you have prints B-2126, A-4752, and A-6122? These are a must have to help trouble shoot some of the 12vdc system. If you don't have these I will bring my copies on my next trip to FTW so we can hook up and swing by the print shop to get you a set of prints that will help you out. These prints may be in the Wiki section here on the forum.

Pamela & Mike

Re: Chassis Battery Voltage

Reply #43 – February 17, 2018, 10:33:42 am

Thanks Chuck that helps clear things up a lot.
When I measured both solenoids from their large post one at a time to ground the voltage was fluctuating so bad it was impossible to get a good reading, I am using a Southwire Digital 600 Volt Clamp Meter.

Guess I need to unplug from shore power and battery ground and clean up the post and a place to ground and retest, if it is still fluctuating would the isolator cause that?

Re: Chassis Battery Voltage

Reply #44 – February 17, 2018, 10:37:44 am

Thanks Mike, When I clean up the others I will get these too while I am at it.

There are some diagrams in the back of big red but from here I am not sure which ones they are, I will look the next time I go out there.

Guess I need to get some new notebook for them as these are shot, I guess the PO used them a lot

Re: Chassis Battery Voltage

Reply #45 – February 17, 2018, 10:56:30 am

Steve,

I know you are working under less-than-ideal weather conditions, which doesn't make this trouble shooting any easier.

No, the fluctuation is not caused by the isolator. The voltage reading on your multimeter should not flucuate, regardless of what is hooked up or not hooked up. I suspect you may be having a hard time finding a good ground point for the NEG probe. All that dirt and rust everywhere is not helping.

SO, (as soon as weather permits) it would be good to get that whole panel cleaned up, as suggested by Mike. Replace any components (like the circuit breakers) that look really bad. They are cheap. Once you have good, clean connections on ALL the cables and wires, you will be in a much better position to solve any remaining problems. Just cleaning up the connections might actually fix all your woes!

My isolator panel looked exactly like yours when we got the coach. After spending a (nice, warm, dry) day under the coach, cleaning and replacing, my panel looked much better (see below). You can do exactly the same thing, and it will make your life easier, believe me.

Re: Chassis Battery Voltage

Reply #46 – February 17, 2018, 11:08:00 am

Thanks Chuck that look nice and clean.

Mother nature is not the nicest this time of year, last weekend it in the 30's and blowing, this weekend it is in the 40's and raining. It does not help that it is 40 miles to just get to the coach but I dont have anyplace at home to park it for a couple of days at a time to work on it as I live on a cul-de-sac and my drive is to steep to get up and not thick enough to hold the coach.

The first time I backed my 5er up the drive I told the DW to let me know if I started dragging anything, well I got it up there and stopped and she came up to the truck and said "you bent some metal things sticking down and knock the spare tire off".

Re: Chassis Battery Voltage

Reply #47 – February 17, 2018, 11:33:41 am

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Re: Chassis Battery Voltage

Reply #48 – February 17, 2018, 11:46:12 am

Thanks Chuck, I added those to my shopping list,

I think I need to add about a 6'x6' indoor/outdoor carpet too, my coach is parked on pea to marble sized Caliche and it is hard on the old knees

Re: Chassis Battery Voltage

Reply #49 – February 17, 2018, 12:10:26 pm

Steve,

With the strange voltage readings you are reporting take a reading right off the alternator taps. Yes when the engine is running. It can be done safely you just have to be extremely careful with the moving belts and pulleys. Unplug from the shore power so we are sure that we are starting with just the alternator voltage and not some stray voltage from a bad isolator.

Pamela & Mike

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